Miniature leadless surface mount lamp with dome and reflector cup
Summary by NHIP
Leadless lamp with dome and reflector
The optical device mounts a light source to an attach pad within a non-conductive mold containing a reflector cup. Two bonding wires extend over the cup edge to connect the source to separate leads, with one wire optionally passing through a recess in the cup top surface.
Claim Score by NHIP
Abstract
A package for a light source is disclosed. In particular, a Plastic Leaded Chip Carrier (PLCC) is described which provides many features offered by traditional surface mount technology lamps, but also has a decreased height, increased light output, and enables a smaller viewing angle as compared to traditional surface mount technology lamps.

Term
Projected expiry 9 September 2031.
- Priority and filed
- Granted
- Today
- Projected expiry
20 claims: 3 independent, 17 dependent
- 1An optical device, comprising:a lead frame comprising an attach pad, a first conductive lead, and a second conductive lead;a non-conductive mold that physically separates the attach pad from both the first conductive lead and the second conductive lead, wherein the non-conductive mold also comprises a reflector cup that encloses the attach pad and is positioned between the attach pad and both the first conductive lead and the second conductive lead such that the first and second conductive leads are not within the reflector cup;a light source mounted to the attach pad;a first bonding wire connecting the light source to the first conductive lead;and a second bonding wire connecting the light source to the second conductive lead.
- 11A package for a light source, comprising:a non-conductive mold substantially surrounding an attach pad that is configured to receive a light source and further including a reflector cup that also surrounds the attach pad and extends above a top surface of the attach pad;a first conductive lead positioned completely outside of the reflector cup on a first outer side surface of the non-conductive mold;and a second conductive lead positioned completely outside of the reflector cup on a second outer side surface of the non-conductive mold.
- 18Broadest claimClaim Score 72, broad(NHIP)A method, comprising:receiving a lead frame that comprises a plurality of attach pads and a plurality of lead fingers, the plurality of attach pads and lead fingers being connected by a series of tie bars;forming a non-conductive mold around at least a portion of the lead frame such that reflector cups are established around at least some of the attach pads and both of the first and second conductive leads are positioned completely outside of the reflector cup;and performing a singulation processes where at least some of the tie bars are removed thereby electrically isolating the attach pads from the lead fingers.
Independent claims3
62 paragraphs in 4 sections, as filed
FIELD OF THE DISCLOSURE
The present disclosure is generally directed toward light emitting devices and packages for the same.
BACKGROUND
Light Emitting Diodes (LEDs) have many advantages over conventional light sources, such as incandescent, halogen and fluorescent lamps. These advantages include longer operating life, lower power consumption, and smaller size. Consequently, conventional light sources are increasingly being replaced with LEDs in traditional lighting applications. As an example, LEDs are currently being used in flashlights, camera flashes, traffic signal lights, automotive taillights and display devices.
Among the various packages for LEDs, an LED package of interest is the Plastic Leaded Chip Carrier (PLCC) package for a surface mount LED. Surface mount LEDs in PLCC packages may be used, for example, in automotive interior display devices, electronic signs and signals, and electrical equipment.
Most existing PLCC package designs do not include a reflector cup, which means that light emitted by a light source contained within a traditional PLCC package is diffused. This has restrained PLCC packages from being used for white lamps.
Another type of LED package is known as a Surface Mount Technology (SMT) lamp. As compared to a PLCC package, the SMT lamp is larger in overall size and it particularly taller in height. This increased size consumes significantly more board space than the PLCC package counterpart thereby (1) reducing the number of pixels in a board of a specified size and (2) increasing the overall thickness of the board. The SMT lamp, however, is capable of limiting the amount of light that is diffused—especially when compared to a PLCC package. This means that SMT lamps are most often employed in white lamps.
It would be advantageous to design a package for a light source that incorporates the benefits of the PLCC package and the SMT lamp in a single package.
BRIEF DESCRIPTION OF THE DRAWINGS
The present disclosure is described in conjunction with the appended figures:
<figref idref="DRAWINGS">FIG. 1</figref> is a cross-sectional view of a light source package and light source in accordance with embodiments of the present disclosure;
<figref idref="DRAWINGS">FIG. 2A</figref> is a top view of a bare lead frame in accordance with embodiments of the present disclosure;
<figref idref="DRAWINGS">FIG. 2B</figref> is an exploded view of a portion of the lead frame depicted in <figref idref="DRAWINGS">FIG. 2A</figref>;
<figref idref="DRAWINGS">FIG. 3</figref> is a cross-sectional view along line <b>3</b>-<b>3</b> depicted in <figref idref="DRAWINGS">FIG. 2B</figref> of a first intermediate product in accordance with embodiments of the present disclosure;
<figref idref="DRAWINGS">FIG. 4A</figref> is a top view of a second intermediate product in accordance with embodiments of the present disclosure;
<figref idref="DRAWINGS">FIG. 4B</figref> is a cross-sectional view along line <b>4</b>-<b>4</b> depicted in <figref idref="DRAWINGS">FIG. 4A</figref>;
<figref idref="DRAWINGS">FIG. 5</figref> is a cross-sectional view of a third intermediate product in accordance with embodiments of the present disclosure;
<figref idref="DRAWINGS">FIG. 6A</figref> is a top view of a fourth intermediate product in accordance with embodiments of the present disclosure;
<figref idref="DRAWINGS">FIG. 6B</figref> is a cross-sectional view along line <b>6</b>-<b>6</b> depicted in <figref idref="DRAWINGS">FIG. 6A</figref>;
<figref idref="DRAWINGS">FIG. 7A</figref> is a cross-sectional view of lead frame having encapsulation cast molded thereto in accordance with embodiments of the present disclosure;
<figref idref="DRAWINGS">FIG. 7B</figref> is a top view of a fifth intermediate product in accordance with embodiments of the present disclosure;
<figref idref="DRAWINGS">FIG. 7C</figref> is a cross-sectional view along line <b>7</b>-<b>7</b> depicted in <figref idref="DRAWINGS">FIG. 7B</figref>;
<figref idref="DRAWINGS">FIG. 8</figref> is a schematic diagram of a transfer molding system in accordance with embodiments of the present disclosure;
<figref idref="DRAWINGS">FIG. 9A</figref> is a top view of a sixth intermediate product in accordance with embodiments of the present disclosure;
<figref idref="DRAWINGS">FIG. 9B</figref> is a cross-sectional view along line <b>9</b>-<b>9</b> depicted in <figref idref="DRAWINGS">FIG. 9A</figref>; and
<figref idref="DRAWINGS">FIG. 10</figref> is a flow diagram depicting a package manufacturing process in accordance with embodiments of the present disclosure.
DETAILED DESCRIPTION
The ensuing description provides embodiments only, and is not intended to limit the scope, applicability, or configuration of the claims. Rather, the ensuing description will provide those skilled in the art with an enabling description for implementing the described embodiments. It being understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope of the appended claims.
Referring now to <figref idref="DRAWINGS">FIG. 1</figref>, an example of a light source package <b>100</b> will be described in accordance with embodiments of the present disclosure. The package <b>100</b> depicted and described herein comprises the advantageous small form-factor available in traditional PLCC packages while simultaneously comprising the optical elements which minimize light diffusion, thereby enabling the package to be used for white lamp applications. In some embodiments, the package <b>100</b> comprises a lead frame <b>104</b> having a plurality of leads separated by a non-conductive mold <b>108</b>. In some embodiments, the mold <b>108</b> may be constructed of any polymer or combination of polymers using extrusion, machining, micro-machining, molding, injection molding, or a combination of such manufacturing techniques. As a non-limiting example, the non-conductive mold <b>108</b> may comprise polyphthalamide (PPA). Accordingly, the terms non-conductive mold, PPA, PPA mold, and pre-mold may be used synonymously herein to refer to the element <b>108</b> that separates the conductive components of the lead frame <b>104</b>.
The lead frame <b>104</b> may comprise a number of leads that are configured to carry electrical current to and from a light source <b>116</b>. In some embodiments, the light source <b>116</b> is physically connected to a mounting surface of the lead frame <b>104</b> and electrically connected to other conductive leads of the lead frame <b>104</b>. Stated another way, the light source <b>116</b> may not be electrically connected to the surface on which it is mounted. In such an embodiment, two or more wires <b>120</b> may be connected to the light source <b>116</b> and each of the two or more wires <b>120</b> may be connected to other leads of the lead frame <b>104</b>. It may also be possible, however, to electrically connect the light source <b>116</b> to a lead on which it is mounted via a conductive adhesive or the like in which case only one wire <b>120</b> may be required to connect the light source <b>116</b> to another one of the conductive leads.
In the embodiment depicted in <figref idref="DRAWINGS">FIG. 1</figref>, the surface onto which the light source <b>116</b> is mounted is not used to carry electrical current to or from the light source <b>116</b>. Rather, the surface of the lead frame <b>104</b> only provides a mounting surface for the light source <b>116</b>. In this particular non-limiting embodiment, a first end of a first wire <b>120</b> is attached (e.g., via soldering, welding, gluing, etc.) at a first point on the top surface of the light source <b>116</b>. A second end of the first wire <b>120</b> is then attached to another lead (e.g., via soldering, welding, gluing, etc.). The creation of an electrical potential between the light source <b>116</b> and the other lead (e.g., a first conductive lead) to which the first wire <b>120</b> is attached causes electrical current to flow to or from the light source <b>116</b> via the first wire <b>120</b>.
Continuing the above example, a first end of a second wire <b>120</b> is also attached to the top surface of the light source <b>116</b>, but at a second point (different from the first point) on the top surface of the light source <b>116</b>. A second end of the second wire <b>120</b> is then attached to yet another lead (e.g., a second conductive lead). The creation of an electrical potential between the light source <b>116</b> and the second conductive lead causes electrical current to flow to or from the light source <b>116</b> via the second wire <b>120</b>. Accordingly, an electrical circuit is created between the two conductive leads and the light source <b>116</b> when an electrical potential is created between the two conductive leads.
The light source <b>116</b>, in some embodiments, comprises an LED or array of LEDs. Where an LED or similar light source is used, one of the bonding wires <b>120</b> is connected to an anode of the light source <b>116</b> whereas another of the bonding wires <b>120</b> is connected to a cathode of the light source <b>116</b>. In some embodiments, the anode and cathode are both on the top light-emitting surface of the light source <b>116</b>. In some embodiments, the anode and cathode are on opposite surfaces of the light source <b>116</b>. Such a light source <b>116</b> may be constructed using known flip-chip manufacturing processes or any other known method for establishing both an anode and cathode on a common side of a light source <b>116</b>. In either configuration, by connecting the anode and cathode of the light source <b>116</b> to two different conductive leads, an electrical potential can be applied to the anode and cathode of the light source <b>116</b> thereby energizing the light source <b>116</b> and causing it to emit light. In some embodiments, the light source <b>116</b> is configured to emit light from its top surface (e.g., away from the lead frame <b>104</b>) when energized. Other suitable light sources include, without limitation, a laser diode, an array of laser diodes, or a combination of laser diodes and LEDs.
In some embodiments, the non-conductive mold <b>108</b>, which electrically separates the various leads of the lead frame <b>104</b>, may comprise a reflector cup <b>112</b>. The reflector cup <b>112</b> may be formed in a top portion of the non-conductive mold <b>108</b>. In some embodiments, the reflector cup <b>112</b> encloses the surface of the lead frame <b>104</b> onto which the light source <b>116</b> is mounted, but does not enclose the conductive leads of the lead frame <b>104</b>. Accordingly, when the light source <b>116</b> is mounted within the reflector cup <b>112</b>, it may be necessary to have each of the bonding wires <b>120</b> extend over the top of the reflector cup <b>112</b>. It should be appreciated that the reflector cup <b>112</b> may be formed in any uniform or non-uniform shape (e.g., circular, elliptical, trapezoidal, square, rectangular, triangular, etc.) depending upon the desired light distribution. In some embodiments, the area of the reflector cup <b>112</b> is larger its top surface as compared to its bottom surface. This means that the reflector cup <b>112</b> gets larger as it extends away from the light source <b>116</b>. In some embodiments, the top surface of the reflector cup <b>112</b> extends above the top surface of the light source <b>116</b>.
In some embodiments, the inner surface of the reflector cup <b>112</b> is coated with a reflective material. Specifically, since the reflector cup <b>112</b> is composed of same material as the non-conductive mold <b>108</b>, it may be necessary to increase the reflectivity of the reflector cup <b>112</b> to improve the optical performance of the package <b>100</b>. In some embodiments, the inner surface of the reflector cup <b>112</b> is coated with a reflective material such as tin, aluminum, etc. to increase the reflectivity of the reflector cup <b>112</b>. The reflective material may be deposited in the reflector cup via any known deposition process such as electroplating, ALD, CVD, magnetron sputtering, and the like.
In some embodiments, the lead frame <b>104</b> may comprise a number of notches <b>132</b> on the conductive leads and/or mounting surface. The notches <b>132</b> may comprise etchings on the top surface of the lead frame <b>104</b> which prevent the non-conductive mold <b>108</b> from flowing into active areas of the lead frame <b>104</b>.
The package <b>100</b> may also comprise an encapsulant <b>124</b> that is configured to encapsulate the light source <b>116</b> and bonding wires <b>120</b> onto the lead frame <b>104</b>. Any number of materials may be suitable for use as the encapsulant <b>124</b>. Examples of such materials include, without limitation, epoxy, silicone, a hybrid of silicone and epoxy, phosphor, a hybrid of phosphor and silicone, an amorphous polyamide resin or fluorocarbon, glass, plastic, or combinations thereof. Furthermore, the encapsulant <b>124</b> may be formed to have one or more light-shaping elements <b>128</b> incorporated therein. Specifically, the encapsulant <b>124</b> can be formed to have one or more curved surfaces which shape the light emitted by the light source <b>116</b> in a desired pattern. As a non-limiting example, the light-shaping element <b>128</b> may comprise a dome, a curved surface, a series of curved surfaces, or any other type of surface for directing light in a predetermined pattern. Accordingly, the encapsulant <b>124</b> can serve multiple purposes of (1) protecting the light source <b>116</b> and/or bonding wires <b>120</b> from physical damage, (2) hermetically sealing the light source <b>116</b> and/or bonding wires <b>120</b>, and/or (3) shaping light emitted by the light source <b>116</b>.
With reference now to <figref idref="DRAWINGS">FIGS. 2A through 10</figref>, a method of manufacturing a package <b>100</b> and the intermediate products obtained thereby will be described in accordance with embodiments of the present disclosure. The manufacturing process begins when a bare lead frame <b>200</b> is received (step <b>1004</b>). <figref idref="DRAWINGS">FIGS. 2A and 2B</figref> depict a suitable example of a bare lead frame <b>200</b> that can be utilized. In some embodiments, the bare lead frame <b>200</b> is constructed of a conductive material such as a metal, metal alloy, or composite. The bare lead frame <b>200</b> may comprise a plurality of sections <b>204</b><i>a</i>, <b>204</b><i>b</i>, <b>204</b><i>c</i>, each of which comprise a plurality of units <b>208</b>. The individual units <b>208</b> will eventually be separated from one another to create a plurality of packages <b>100</b> from the bare lead frame <b>200</b>. Although the bare lead frame <b>200</b> is depicted as comprising three sections <b>204</b><i>a</i>, <b>204</b><i>b</i>, <b>204</b><i>c</i>, it should be appreciated that a bare lead frame <b>200</b> may comprise a greater or lesser number of sections without departing from the scope of the present disclosure.
<figref idref="DRAWINGS">FIG. 2B</figref> depicts additional details of an individual unit <b>208</b>. In particular, each unit <b>208</b> may comprise an attach pad <b>212</b>, a plurality of lead fingers <b>216</b>, and a plurality of tie bars <b>220</b> connecting the attach pad <b>212</b> to the plurality of lead fingers <b>216</b>. In some embodiments, the attach pad <b>212</b> corresponds to an area of the unit <b>208</b> onto which a light source <b>116</b> may eventually be mounted. Each of the lead fingers <b>216</b> may correspond to areas which will eventually become conductive leads for the package <b>100</b>.
As can be seen in <figref idref="DRAWINGS">FIG. 2B</figref>, a single attach pad <b>212</b> may be surrounded by the plurality of lead fingers <b>216</b> and each of the plurality of lead fingers <b>216</b> may not only be positioned between different attach pads <b>212</b>, but they may also extend from both sides of a tie bar <b>220</b>. Accordingly, a single lead finger <b>216</b> may be separated into two different conductive leads of two different packages <b>100</b> once the units <b>208</b> have been singulated by cutting the tie bars <b>220</b>. By allowing a single lead finger <b>216</b> to eventually be separated into two different conductive leads, the utilization of space on the bare lead frame <b>200</b> is maximized and material costs are minimized. Therefore, a useful configuration of a single unit <b>208</b> will comprise a single attach pad <b>212</b> surrounded substantially uniformly by four lead fingers <b>216</b>. As a non-limiting example, each of the four lead fingers <b>216</b> may be separated from the attach pad <b>212</b> by substantially the same distance (e.g., within a machining tolerance) and may be distributed at 90 degree increments around the attach pad <b>212</b>. It should be appreciated, however, that an attach pad <b>212</b> can be surrounded by a greater or lesser number of lead fingers <b>216</b> (uniformly or non-uniformly) without departing from the scope of the present disclosure.
Although the attach pad <b>212</b> is depicted as having generally square dimensions and the lead fingers <b>216</b> are depicted as having generally elliptical dimensions, it should be appreciated that the attach pads <b>212</b> and lead fingers <b>216</b> may be formed in any number of shapes without departing from the scope of the present disclosure. For instance, the attach pads <b>212</b> and lead fingers <b>216</b> may be generally circular in shape.
In some embodiments, one or more of the attach pads <b>212</b> may comprise a notch <b>224</b> on a single side thereof. The notch <b>224</b> can be used as an orientation indicator during the manufacturing process of the package <b>100</b>. In particular, the notch <b>224</b> can be referenced during various manufacturing stages to ensure that the appropriate manufacturing steps are being performed on the appropriate portions of the bare lead frame <b>200</b>.
The manufacture of the package <b>100</b> continues when a tape <b>304</b> is applied to a selected surface of the bare lead frame <b>200</b> (step <b>1008</b>). In some embodiments, the tape <b>304</b> may correspond to a thermally-stable adhesive tape that is adhered to a bottom surface of the bare lead frame <b>200</b>.
The cross-sectional view depicted in <figref idref="DRAWINGS">FIG. 3</figref> also shows additional features of the bare lead frame <b>200</b>. Specifically, the cross-sectional characteristics of the attach pads <b>212</b> and lead fingers <b>216</b> are shown in more detail. In some embodiments, the bare lead frame <b>200</b> may comprise a half-etched frame to facilitate stable anchoring of the non-conductive mold <b>108</b> to the lead frame <b>104</b>. More particularly, a top section <b>308</b> of the bare lead frame <b>200</b> may not be etched whereas a bottom section <b>312</b> of the bare lead frame <b>200</b> is etched. This causes a gap <b>316</b> between the attach pad <b>212</b> and lead finger <b>216</b> to have a t-shaped cross-section. Even more specifically, the width of the gap <b>316</b> in the bottom section <b>312</b> of the bare lead frame <b>200</b> may be larger than the width of the gap <b>316</b> in the top section <b>308</b> of the bare lead frame <b>200</b>. This t-shaped cross-section facilitates the stable anchoring of the non-conductive mold <b>108</b> to the lead frame <b>104</b> in the finished package <b>100</b>. In some embodiments, the top section <b>308</b> and bottom section <b>312</b> are of substantially the same thickness (e.g., within a machining tolerance) such that the top section <b>308</b> represent the top half of the bare lead frame <b>200</b> and the bottom section <b>312</b> represents the bottom half of the bare lead frame <b>200</b>. Such a configuration is not required, however. In some embodiments, the top section <b>308</b> may be thicker than the bottom section <b>312</b> or the bottom section <b>312</b> may be thicker than the top section <b>308</b>. Even more particularly, and as a non-limiting example, the total thickness of the bare lead frame <b>200</b> may be between about 0.1 mm and 0.3 mm and in some embodiments may be about 0.2 mm.
Referring back to <figref idref="DRAWINGS">FIG. 10</figref>, after the tape <b>304</b> has been attached to the bare lead frame <b>200</b>, the process continues by molding the non-conductive mold <b>404</b> around the bare lead frame <b>200</b> (step <b>1012</b>). An intermediate product obtained by this process step is depicted in <figref idref="DRAWINGS">FIGS. 4A and 4B</figref>.
The non-conductive mold <b>404</b> may be the same or identical to the non-conductive mold <b>108</b> except that it is not singulated. The same statement is true with respect to the bare lead frame <b>200</b> and lead frame <b>104</b>.
In some embodiments, this step is completed by placing the bare lead frame <b>200</b> having the tape <b>304</b> attached thereto into a transfer mold system. Specifically, the bare lead frame <b>200</b> and tape <b>304</b> may be placed between a bottom die set <b>412</b> and a top die set <b>416</b> of a transfer mold system. The bottom die set <b>412</b> may comprise a generally flat surface that interfaces with the tape <b>304</b>. The top die set <b>416</b>, however, may comprise a number of features or indentations on the surface that interfaces with the top surface of the bare lead frame <b>200</b>. The features or indentations in the top die set <b>416</b> may be positioned relative to the bare lead frame <b>200</b> to establish the reflector cups <b>112</b> of the non-conductive mold <b>404</b> around each attach pad <b>212</b>. Specifically, the features or indentations in the top die set <b>416</b> may be positioned proximate to notches <b>132</b> that are established on the top surfaces <b>420</b> of the lead fingers <b>216</b> and the top surfaces <b>424</b> of the attach pads <b>212</b>. The features or indentations in the top die set <b>416</b> along with the notches <b>132</b> substantially inhibit the non-conductive mold <b>404</b> from covering the entire top surface of either the attach pad <b>212</b> or lead finger <b>216</b>.
In accordance with at least some embodiments of the present disclosure, the entirety of the top surface <b>420</b> of each lead finger <b>216</b> is left exposed (e.g., not covered with the non-conductive mold <b>404</b>). On the other hand, a portion of the top surface <b>424</b> of the attach pad <b>212</b> is covered with the non-conductive mold <b>404</b>. Particularly, the portion of the top surface <b>424</b> of the attach pad <b>212</b> is covered with the non-conductive mold <b>404</b> to establish the reflector cups <b>112</b> around each attach pad <b>212</b>. In some embodiments, the remaining area of the attach pad <b>212</b> that is left exposed is completely enclosed by the reflector cup <b>112</b>. The still-exposed area of the attach pad <b>212</b> may be substantially circular or may have any other suitable shape.
In some embodiments, the height of the reflector cup <b>112</b> may be substantially similar to the thickness of the bare lead frame <b>200</b>. Accordingly, as a non-limiting example, the reflector cup <b>112</b> may be between about 0.1 mm and 0.3 mm in height and in some embodiments may be about 0.2 mm in height.
After the non-conductive mold <b>404</b> is established about the bare lead frame <b>200</b>, the manufacturing process continues by attaching a light source <b>116</b> to the top surface <b>424</b> of each attach pad <b>212</b> and also by connecting bonding wires <b>120</b> between the light source <b>116</b> and the top surface <b>420</b> of the lead fingers <b>216</b> (step <b>1016</b>). In this step, a light source <b>116</b> may be glued, soldered, welded, or otherwise physically connected to the top surface <b>424</b> of an attach pad <b>212</b> that is still exposed and within the reflector cup <b>112</b>.
Then, depending upon the nature of the light source <b>116</b> (e.g., depending upon whether both the anode and cathode are on the top surface of the light source <b>116</b> or whether both of the anode and cathode are on the bottom surface of the light source <b>116</b>, which is connected to the attach pad <b>212</b>), one or more bonding wires <b>120</b> are connected between the light source <b>116</b> and a lead finger <b>216</b> that is outside the reflector cup <b>112</b>. Accordingly, it may be required to loop one or more of the bonding wires <b>120</b> over the reflector cup before or after it has been attached to the light source <b>116</b> and/or lead finger <b>216</b>. In some embodiments, the bonding wires <b>120</b> may comprise a cross-sectional profile that is one of square, rectangular, and circular.
<figref idref="DRAWINGS">FIG. 5</figref> depicts one embodiment of an intermediate product obtained by step <b>1016</b> where the bonding wire <b>120</b> is looped over a fully-formed reflector cup <b>112</b>. In this embodiment, the bonding wire <b>120</b> may comprise a loop height of between about 10 mils and 15 mils and in some embodiments the bonding wire <b>120</b> comprises a loop height of about 12 mils (e.g., about 0.3048 mm).
<figref idref="DRAWINGS">FIGS. 6A and 6B</figref> depict another embodiment of an intermediate product obtained by step <b>1016</b> where the reflector cup <b>112</b> formed in the non-conductive mold <b>404</b> comprises one or more recesses <b>604</b> in its top surface. In some embodiments, a recess <b>604</b> is established directly between the attach pad <b>112</b> and one of the lead finger <b>216</b>. In some embodiments, a first recess <b>604</b> is established between the attach pad <b>112</b> and one of the adjacent lead fingers <b>216</b> while a second recess <b>604</b> is established between the attach pad <b>112</b> and another of the adjacent lead fingers <b>216</b>. In some embodiments, a separate recess is established between the attach pad <b>112</b> and each of the adjacent lead fingers <b>216</b>.
In any of the above embodiments, the depth of the recess <b>604</b> may be in substantially the same plane as the top surface of the light source <b>116</b>. Alternatively, one or more of the recesses <b>604</b> can still be higher than the top surface of the light source <b>116</b>. Still further in the alternative, one or more of the recesses <b>604</b> can be below the top surface of the light source <b>116</b>.
As compared to the embodiment of <figref idref="DRAWINGS">FIG. 5</figref>, the one or more recesses <b>604</b> make it possible to lower the loop height of the bonding wires <b>120</b> that traverse the reflector cup <b>112</b>. Thus, the bonding wire <b>120</b> can travel a more direct path from the light source <b>116</b> to the lead finger <b>216</b>. In some embodiments, it may be possible to reduce the wire loop height to about 6 mils or less. It may not be preferable, however, to utilize the one or more recesses <b>604</b> where precise light radiation patterns are required of the package <b>100</b>.
Once the light sources <b>116</b> have been attached to the bare lead frame <b>200</b> and the bonding wires <b>120</b> have been appropriately connected, the manufacturing process may continue with an encapsulation step. However, there are a number of possible ways to encapsulate the intermediate product of <figref idref="DRAWINGS">FIG. 5</figref> or <figref idref="DRAWINGS">FIGS. 6A and 6B</figref>. Specifically, either a casting process or a transfer mold process can be performed to achieve the encapsulation step. Accordingly, the method proceeds by first determining whether the encapsulation step will be done via casting or via a transfer mold process (step <b>1020</b>).
<figref idref="DRAWINGS">FIGS. 7A-C</figref> depict aspects of the encapsulation step via the casting process. Specifically, if a casting process is to be employed, then the intermediate product obtained after step <b>1016</b> is pre-dipped in the reflector cup <b>112</b> with a first encapsulant and the encapsulant is partially cured (step <b>1024</b>). In particular, the first encapsulant can be pre-dipped onto the reflector cup <b>112</b> with any dispensing method using time pressure, auger, piston pumps or jet technology, etc. The dispensing of the first encapsulant is to fill up the cavity of the reflector cup <b>112</b> allowing the air to escape within the cavity of the reflector cup <b>112</b> before the intermediate product <b>712</b> is fully encapsulated with second encapsulant <b>708</b> in the subsequent process (step <b>1032</b>). This pre-dipping and partial cure also causes the light source <b>116</b> and bonding wires <b>120</b> to be more securely fixed to the bare lead frame <b>200</b>. Thereafter, the tape <b>304</b> is removed from the bottom surface of the bare lead frame <b>200</b> (step <b>1028</b>) and a casting process is performed (step <b>1032</b>). Detape (step <b>1028</b>) is to remove the tape on the encapsulant <b>404</b> where the tape is covering the exit of the air vent <b>716</b>. The air within the cavity of the frame mold cup <b>704</b> may escape via the open-end air vents <b>716</b> when the second encapsulant <b>708</b> occupying the space of the cavity in the frame mold cup <b>704</b>.
<figref idref="DRAWINGS">FIG. 7A</figref> depicts the intermediate product <b>712</b> during the casting process where the intermediate product <b>712</b> is placed within a frame mold cup <b>704</b> and the encapsulant <b>708</b> is supplied to the cavity of the frame mold cup <b>704</b>. Similar to the bare lead frame <b>200</b> and non-conductive mold <b>404</b>, the encapsulant <b>708</b> may be similar or identical to encapsulant <b>124</b> except that it is not yet singulated.
As can be seen in <figref idref="DRAWINGS">FIG. 7A</figref>, since the bare lead frame <b>200</b> comprises a plurality of units <b>208</b>, the frame mold cup <b>704</b> may comprise a corresponding number of features that form the light-shaping element <b>128</b> for each package <b>100</b>.
Referring to <figref idref="DRAWINGS">FIGS. 7A and 7B</figref>, it should also be noted that for the casting process, one or more air vents <b>716</b> may be established in the non-conductive mold <b>404</b> in each unit <b>208</b>. Specifically, the air vents <b>716</b> may be provided to allow the release of air that is trapped during the casting process. The air vents <b>716</b> may be positioned anywhere within the non-conductive mold <b>404</b> between the attach pad <b>212</b> and the tie bars <b>220</b>. It may be preferable not to position the air vents <b>716</b> directly between the attach pad <b>212</b> and lead finger <b>216</b>, especially since the reflector cup <b>112</b> is positioned between the attach pad <b>212</b> and lead finger <b>216</b>. It should be appreciated that each unit <b>208</b> may have one, two, three, four, or more air vents <b>716</b>. It should also be appreciated that each unit <b>208</b> may not necessarily require its own air vent <b>716</b> as long as a suitable number of air vents <b>716</b> are distributed about the entirety of the non-conductive mold <b>404</b>.
Once the casting process is completed, the separate packages <b>100</b> are created by separating the units <b>208</b> in a singulation process (step <b>1036</b>). <figref idref="DRAWINGS">FIGS. 9A and 9B</figref> depict additional details of the singulation process. In particular, the singulation process is the process whereby each of the units <b>208</b> are separated from one another and a plurality of discrete packages <b>100</b> are obtained thereby. More specifically, during the singulation process, a saw blade <b>904</b> or similar cutting apparatus is used to cut through the tie bars <b>220</b> connecting each of the lead fingers <b>216</b>. As can be seen in <figref idref="DRAWINGS">FIG. 9A</figref>, the saw blade <b>904</b> may comprise a thickness that is substantially identical to a thickness of the tie bars <b>220</b> at their thickest part. Furthermore, the saw blade <b>904</b> may cut into the intermediate product such that each of the lead fingers <b>216</b> are cut in half and the attach pad <b>212</b> is electrically isolated from all of the lead fingers <b>216</b>. Thus, a separation gap <b>908</b> may be created between each of the units <b>208</b> and the final package <b>100</b> can be achieved.
Referring back to step <b>1020</b>, if the encapsulation will be performed via a transfer mold process, then the method continues by first performing the transfer mold process to secure the encapsulant <b>708</b> to the intermediate product <b>712</b> (step <b>1040</b>). As can be seen in <figref idref="DRAWINGS">FIG. 8</figref>, the transfer molding process may utilize a transfer mold system <b>804</b> that includes a mold having a plurality of air vents <b>808</b> therein and a mold feeder or runner <b>812</b>. The material of the encapsulant <b>708</b> may be fed into the transfer mold via the mold runner <b>812</b> and the air from within the cavity of the transfer mold may escape via the air vents <b>808</b> due to the encapsulant <b>708</b> occupying the space of the cavity in the transfer mold. After the encapsulant <b>708</b> has been completely injected via the transfer mold process, the method continues with the removal of the tape <b>304</b> (step <b>1044</b>) and then singulation of the individual units <b>208</b> (step <b>1048</b>). The singulation step <b>1048</b> may be similar or identical to the singulation step <b>1036</b>.
After the individual packages <b>100</b> have been obtained, the method may continue by preparing the packages <b>100</b> for sale (either individually or in bulk).
Advantages obtained by employing the embodiments discussed herein are many. In particular, a package <b>100</b> can be manufactured that achieves an increased light output, enables a smaller viewing angle, and enables white lamps that are compatible with the PLCC standard. Furthermore, multiple dice can be packaged simultaneously either within a single package <b>100</b> or across a plurality of packages <b>100</b>. Further still, a package <b>100</b> with the above qualities can be achieved while also having a smaller form-factor than previous SMT lamps. The package <b>100</b> also provides a direct thermal path to the circuit board onto which the package <b>100</b> is mounted (e.g., thermal path via the attach pad <b>212</b> of the lead frame <b>104</b>). Also, the manufacturing process described herein leverages chip LED processing techniques, thereby minimizing the capital investment required to produce the package <b>100</b> described herein.
Specific details were given in the description to provide a thorough understanding of the embodiments. However, it will be understood by one of ordinary skill in the art that the embodiments may be practiced without these specific details. For example, circuits may be shown in block diagrams without unnecessary detail in order not to obscure the embodiments. In other instances, well-known circuits, processes, algorithms, structures, and techniques may be shown without unnecessary detail in order to avoid obscuring the embodiments.
While illustrative embodiments of the disclosure have been described in detail herein, it is to be understood that the inventive concepts may be otherwise variously embodied and employed, and that the appended claims are intended to be construed to include such variations, except as limited by the prior art.
Contents4
11 sheets
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Every citation, both waysCites: the store holds 8 of 9
| Document | Relation | Office | Cited during |
|---|---|---|---|
| US2011134629A1 | Cites | United States of America | Applicant |
| US5130604A | Cites | United States of America | Applicant |
| US6086225A | Cites | United States of America | Applicant |
| US6943433B2 | Cites | United States of America | Search report |
| US7655958B2 | Cites | United States of America | Search report |
| US8044418B2 | Cites | United States of America | Search report |
| US8134173B2 | Cites | United States of America | Search report |
| US20110134629A1 | Cites | United States of America | Applicant |
| Pohl, Andreas, “‘SMT Lamps’: Merging Through-Hole and Surface-Mount LED Technology”, ECN, available at http://www.ecnmag.com/Articles/2011/04/App-Solutions/SMT-Lamps/, Apr. 6, 2011, 6 pages. | Non-patent | – | Applicant |
| Avago Technologies, “ASMT-FJ30 Mini Surface Mount AF LED”, Data Sheet, AV02-0996EN, Jan. 28, 2008, 6 pages. | Non-patent | – | Applicant |
| Pohl, Andreas, "'SMT Lamps': Merging Through-Hole and Surface-Mount LED Technology", ECN, available at http://www.ecnmag.com/Articles/2011/04/App-Solutions/SMT-Lamps/, Apr. 6, 2011, 6 pages. | Non-patent | – | Applicant |
| Avago Technologies, "ASMT-FJ30 Mini Surface Mount AF LED", Data Sheet, AV02-0996EN, Jan. 28, 2008, 6 pages. | Non-patent | – | Applicant |
2 members in 1 office
Priority claims2
| Document | Office | Kind | Date |
|---|---|---|---|
| 201113205396 | United States of America | A | |
| US201113205396 | – | – | – |
Members2
| Document | Office | Kind | |
|---|---|---|---|
| US2013037837A1 | United States of America | A1 | |
| US8513693B2This record | United States of America | B2 |
41 transactions on the USPTO file
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Numbers
- Publication
- 08513693
- Publication, DOCDB
- 8513693
- Publication, EPODOC
- US8513693
- Application
- 13205396
- Application, DOCDB
- 201113205396
- Application, EPODOC
- US201113205396
Titles
- English
- Miniature leadless surface mount lamp with dome and reflector cup
Patent term adjustment
- A delay
- +32 daysthe office missed an examination deadline
- Net adjustment
- 32 days
Classification
- CPC, 7
- H10H20/8506
- H10H20/853
- H10H20/856
- H10W72/0198
- H10W90/756
- H10W74/10
- H10W74/00
- IPC, 1
- H01L33 62
- USPC, 11
- 257098000
- 257088000
- 257089000
- 257099000
- 257666000
- 257676000
- 257E33059
- 257E33061
- 257E33072
- 438026000
- 438027000